A conventional laundry treating apparatus includes a cabinet defining an exterior appearance, a tub mounted in the cabinet, a drum rotatably oriented in the tub to wash laundry and a motor fixed to the drum to rotate the drum, with a shaft penetrating the tub.
The drum is likely to fail in keeping dynamic equilibrium or dynamic balance according to the location of the laundry loaded in the drum, while rotating the laundry.
The term of dynamic equilibrium or dynamic balance means a status where a centrifugal force or a moment created by a centrifugal force becomes “0” (zero) with respect to a shaft while a rotating body is rotating. If mass distribution of a rigid body is uniform with respect to a shaft, it can be said that dynamic equilibrium or dynamic balance is maintained.
When applied to such a laundry treating apparatus, a dynamic equilibrium state or a dynamic-balanced state can be understood as a state where mass distribution of laundry with respect to the shaft of the drum is within a permissible range while the drum accommodating laundry is rotating.
In contrast, a dynamic-unbalanced state of the laundry treating apparatus can be understood as a state where mass distribution of laundry with respect to the shaft of the rotating drum is not uniform. In the laundry treating apparatus, the dynamic-unbalanced state occurs when the laundry is not distributed uniformly.
The rotating drum in the dynamic-unbalanced state is also vibrating and the vibration of the rotating drum is delivered to the tub or the cabinet, such that the vibration may cause a disadvantage of noise.
Some of the conventional laundry treating apparatuses include balancing units for compensating the unbalance of the drum. Such balancing units provided in the conventional laundry treating apparatuses are provided as ball balancers or fluid balancer having balls or liquid provided in a housing fixed to the drum.
The dynamic-unbalanced drum has the highest rotation speed when the laundry as an unbalance inducing factor is passing the lowest point of a drum rotation locus and the lowest rotation speed when the laundry as the unbalance inducing factor is passing the highest point of the drum rotation locus.
Accordingly, the ball balancer or fluid balancer provided in the conventional laundry treating apparatus controls unbalance by implementing the ball or fluid to move toward the lowest point of the drum rotation locus when the laundry as the unbalance inducing factor is moving toward the highest point.
However, it is difficult to solve the dynamic balance of the drum immediately (or to settle the dynamic balance actively), using the structure of such the balancer mentioned above.